The present invention relates to an improved method for performing automated immunoassays, and in particular to performance of enzyme-linked immunosorbent assays (ELISA). Methods of automating ELISA are known, as disclosed for example in U.S. Pat. No. 4,708,929. Such automated techniques may involve detection of fluorescence, reflectance, optical density, radioactivity, and other physical characteristics.
In performing such assays, samples to be tested are introduced into individual microwells within a microstrip or microplate. One example of a microstrip is shown in FIG. 1A. Each microstrip may optionally be placed in a holder, as shown in FIG. 2A. A plurality of microstrips are placed in a carrier, the carrier then being inserted into the instrument. The instrument, which may measure one of the above-measured characteristics, is focused on the microwells in a given microstrip, and corresponding data derived from the read-out of the device (as a function of optical density, radioactivity, etc.). The data which is derived from the device read-out identifies the presence or absence of a given analyte (for example, HIV or clamydia).
Conventionally, at the beginning of the test, an operator of the device will input information (via a keyboard or other means) to tell the instrument what analyte is being tested for, so that the read-out may be correlated appropriately with a reference. For example, if the test is being conducted to determine the presence of chlamydia in the samples, the read-out should be correlated with a reference value corresponding to presence of chlamydia in the sample.
Because operator input is required, the degree of automation of the operation is less than complete. Also, since the strips are not visually or otherwise distinguishable once they are pretreated with a specific analyte, operator error is possible. It would be desirable to automate the process yet further, by providing identification of what disease is to be tested for in a particular strip, without the need for operator interaction.